Traumatic brain injury (TBI) is the most common cause of acquired disability in childhood. Children with impairment following moderate to severe injury subsequently show negligible rates of change in motor function after one year. Adults with chronic stroke have demonstrated improvement in motor function years following insult with constraint-induced movement therapy (CI therapy). Neuroimaging correlates of recovered function in adult hemiplegic extremities reveal differences in cortical activation patterns in comparison with normal patterns The objective of this proposal is to organize a research team that will develop a clinical trial of CI therapy in children with hemiplegia persisting more than one year following TBI. The study proposed for development would be prospective, randomized, crossover, and single-blinded, to test the major hypotheses: 1) that changes in motor function in hemiplegic extremities occur at a higher rate, to a greater extent, and with more qualitative improvement following CI therapy, in comparison to traditional physical and occupational therapy and 2) that improvement following CI therapy is accompanied by discernable differences in patterns of cortical activation on functional magnetic resonance imaging. While the emphasis is intended to be focused on forced use of the upper extremity in developing the study, consideration will also be given to developing a component of forced weight shift for the lower extremity. The planning process would include development of the protocols, selection of outcome measures, and methods of statistical analyses. Individual rate-of-change modeling will explored for inclusion in the statistical methods. Additional brain mapping correlates of changes in functional motor activity will be considered for inclusion in the clinical trial, including transcranial magnetic stimulation paradigms. Lessons learned from designing an innovative study to evaluate the effectiveness of rehabilitative intervention in improving motor function after pediatric TBI and the accompanying changes in cortical reorganization may be generalizable to studies of interventions directed toward other domains of dysfunction and in other study populations. Functional MRI offers clear potential to increase our understanding between rehabilitation efforts, functional recovery, and neurological reorganization in ways that could direct the design of future interventions in pediatric rehabilitation.